1. Field of the Invention
The present invention relates principally to a semiconductor device and a packaging method thereof, and more particularly to a semiconductor device comprising a light-receiving element which operates in response to light and a light-emitting element which emits light, for example a semiconductor device including an image sensor such as a CCD or CMOS, a light-emitting diode, a photoelectric conversion element, and so on, and a packaging method thereof.
2. Description of the Related Art
Conventionally, when packaging a semiconductor device comprising a light-receiving element and light-emitting element manufactured in wafer form, the wafer on which the light-receiving elements and/or light-emitting elements are formed is cut into individual semiconductor chips 4410 by means of dicing, as shown in FIG. 44. The individual semiconductor chip 4410 is then mounted on a ceramic header 4420, whereupon an electrode 4430 of the semiconductor chip mounted on the ceramic header 4420 is electrically connected to a conductor portion of the ceramic header 4420 by wire bonding 4440. A lid 4450 which transmits light is then adhered to the ceramic header 4420. This is a typical semiconductor device packaging method.
Japanese Patent Application Publication Kokai No. 2002-329850 (hereinafter, referred to as “patent document-1”) and Japanese Patent Application Publication Kokai No. 2004-111792 (hereinafter, referred to as “patent document-2”) may be cited as examples of packaging methods which do not use a ceramic header.
The patent document-1 discloses a semiconductor device constituted by a semiconductor chip whose side face and rear face are coated with a resin, and whose top face comprises an electrode pad that is electrically connected to a light-receiving element, and a glass substrate having a first face which contacts the top face of the semiconductor chip. Thus an electrode pattern formed over the resin-coated side face and rear face of the semiconductor device, a conductive pattern provided on the first face of the glass substrate, and the light-receiving element are electrically connected. In a manufacturing method of the patent document-1, a wafer comprising the light-receiving element and a translucent substrate comprising a lens are formed separately, and individual ICs are made by cutting after the wafer and translucent substrate are adhered together.
The patent document-2 discloses a semiconductor device comprising a semiconductor chip in which top face, side face, and bottom face are coated with a transparent resin, and the top face is formed with a photoresponsive element, and a transparent substrate formed on the top face side of the semiconductor chip at a remove therefrom. Thus wiring coated with a plurality of resin layers, which extends around the periphery of the semiconductor chip and is connected electrically to the photoresponsive element, is electrically connected to connecting means for connecting the tip end of the wiring to an external electrode.
With packaging methods using a ceramic header, the semiconductor chip is mounted on a ceramic header having a greater exterior dimension than that of the semiconductor chip, thereby increasing the exterior dimension of the packaged semiconductor device. Moreover, space must be provided above the semiconductor chip for the wire bonding and lid, thereby increasing the thickness of the packaged semiconductor device, and hence it is difficult to achieve a reduction in size. Packaging methods using a ceramic header are also problematic in that costs are higher than in packaging methods using resin.
Further, in the patent document-1, the electrode pattern formed on the side face is exposed, and hence a short circuit is more likely to occur between electrode patterns when the electrode patterns come into contact. Moreover, during handling of the individual packages, the electrode pattern may become disconnected when the electrode pattern contacts a semiconductor holder used for lifting the semiconductor device. Also with the manufacturing method of the patent document-1 the wafer comprising the light-receiving element and the translucent substrate comprising the lens are formed separately and then adhered together, leading to alignment errors which result in a decrease in productivity.
In the patent document-2, the side face of the semiconductor device is constituted by a sealant using a plurality of resin layers, and hence cracks or the like may appear at the boundary line parts of these resin layers during a heating process such as reflow processing, possibly causing the semiconductor device to break. Further problems such as corrosion of the wiring layers formed in the semiconductor device due to moisture infiltrating through the boundary lines of the resin layers, and abnormalities in the characteristics of the semiconductor element due to the incoming moisture, may lead to a breakdown in the functions of the semiconductor element, resulting in a reduction in the long-term reliability of the device.